Oscillation control



Jan. 21, 1930.

H. J. J. M. DE R. DE BELLESCIZE 1,744,618

OSCILLATION CONTROL 2 Sheets-Sheet 1 Filed March 10, 1923 Y 3440244 501, HJJ. MDER. DEBELLESCI ZE 1930. H. J. J. M. DE R. DE BELLESCIZE OSCILLATION CONTROL Filed March 10, 1925 2 Sheets-Sheet 2 avweutoz H.J.d.M-DER.DEBELLE6CIZE \ms/ GM! Patented Jan. 21, 1930 v v UNITED STATES PATENT OFFICE HENRI JEAN JOSEPH MARIE DE REGNAULD DE BELLESCIZE, OF PARIS, FRANCE OSCILLATION common Application filed March 10, 1923, Serial No. 624,286, and in France March 29, 1922.

The present invention has for its object to reduce the effect of atmospheric disturbances on wireless telegraph and telephone receiv-' ers.

It has already been suggested for this purpose to associate with receiving circuits an element such as an electron tube or a rectifier contact which is suitably de-sensitized or also a suitably controlled microphonic contact. Under these conditions such element does not interfere with the receiving of the signals but operates under the control of the disturbances either for compensating the disturbing current which would result in the indicating apparatus or for rapidly damping the resulting oscillations The present invention has for its object to provide a system of this character. The invention is characterized by the association of a three-electrode relay tube with the resonator in which it is desired rapidly to damp the disturbing oscillations. The association or combination is such that the plate-filament space of the tube is in shunt between two 2 suitably selected points of the resonator, a

suitable, usually feeble, potential difference being in series with said space. Said space performs the function of a variable resistance for the damping because, in accordance with the present invention, the grid of the tube is connected preferably through a current source with a point of the receiving circuit which is selected in such a manner that under the control of the disturbances to be damped it presents a positive rise of suitable value of its mean potential difference with respect to the filament of the tube in question.

Obviously, the invention may be subjected to various modifications. It is possible to ap ply it a number of times within one and the same receivingstation, i. e. to provide a plu rality of damping tubes each having forits function the damping of one or a plurality of resonant circuits of the station, audit-his in combination with the control of all the grids by varying the potential of one point, etc. 'Finally under certain circumstances, the arrangement may be completed by combining it with other anti-atmospheric arrangements and more particularly with limiting arrangements. 7

The invention will be more readily understood with the aid of the following descrip tion and enclosed drawings whichexemplify a few embodiments of the in which present invention,

Fig. 1 shows certain apparatus explaining I Fig. 6 shows an alternative modification for controlling the damping tube, and

Fig. 7 shows still another modification the same purpose. r

The principle consists in this; rapidly to damp all oscillations which are stronger thanthe signal by associating a few of the receivmg resonators with an equal number of resistances the value R of which depends on the amplitude of the oscillations. This a s sociation is schematically illustrated in Fig.

for V 1 in which a variable resistance R is connected with the terminals of condenser .C. The

r 1 damping factor will be of which is that of resonator LC, and the other 7%, is due to the damping resistance Rt The element constitutingthis resistance must be such that its value R be practically infinite in the normal service and drop to as low a value as possible as soon as under the control of e. g. anaperiodic disturbance the resonator becomes the seat of an oscillation having an amplitude which is considerably larger than that of the signal.

In practice the variable resistance R is composed of the plate-filament circuit of a three-electrode tube, the grid potential, of

ice

which is controlled by the amplitude of the oscillations received. The curves illustrating the plate current J as a function of weak positive and negative values of the plate potential U, have the formshown in Fig. 2. The characteristic merges with the abscissa 7'=zero) when the grid potential '1; is slightly negative and will rapidly increase as soon as this potential 12 increases. Assuming that the mean potential of the plate is adjusted to a certain value U the internal resistance R of the plate filament circuit will be infinite when the grid potential Q; will be equal or inferior to to; for grid voltage o=o2 this resistance will have the following finite value The association of a resonator LC with a tube T adapted to serve as a damping device is schematicallyillustrated in Fig. 3. The plate and filament of the tube T constitute the resistance R and are respectively connected with the plates of the condenser C. By means tial of this plate. This increase is transmitted to the grid of the tube T through the agency of a current source S adjusted to such a value that under the control of a signal the potential 02 of this grid will attain the value o for which the resistance R will cease to be infinite. In practice this result is obtained by reducing the number of cells in the battery S until the intensity of the signal tends to weaken.

Fig. 4 illustrates a plurality of resonators L C -L C all connected with tubes T T T. It is advisable to provide means for preventing the return to the first amplifying stages of high frequency currents which pass through the detector. This is accomplished by means of a certain number of filtering circuits M C M C which comprises self inductions l\ M and capacities C, C opposing the rectified currents by reactances which arepractically equal to the internal resistance of the detector tube. batteries S S S brin the grids of the amplifying tubes to suitable potentials, which are usually slightly different from U which is the potential of the plate of tube T.

The present arrangement is particularly adapted for receiving very long waves. It may be combined to good effect with a limiting means X whereby disturbing oscillations which occur in the listening apparatus G The will be reduced in their duration and will be limited in their amplitude.

The grouping and nature of the resonators to be damped maybe as desired. An open or a closed antenna may be used, or a group are subjected to variations of potential produced in the resistance R by the oscillations rectified in the detector tube D.

A source B serves for bringing to a suitable negative value the potential at point 0 from which the grids of the tubes T T T etc. are controlled.

A system composed of self inductions M and capacities N prevents the passage of high frequency oscillations which traverse the. de tector D towards the tubes T T T etc.

A high frequency amplifier A of any suitable type or strength may precede the detector D. w

Any well known registering apparatus G may be used.

By means of suitable connections invariable relative potentials will be maintained at the different sources S S S etc. from which current is supplied to the tubes.

Furthermore, the functioning of the receiving oscillations on the grids of the damping tubes T T T etc. may be varied.

In the example shown in Fig. 5, the operation is the same as that previously described.

Fig. 6 represents a circuit arrangement in which the oscillations rectified by detector tube D act on the grids T T T etc. (a single .triode damping tube is shown for the sake of simplicity) through the agency of a transformer K. Instead of the oscillations being translated always by a positive variationof the potential common to the grid T T etc. as was the case in the circuit arrangement shown in Fig. 1, the oscillations are translated by positive and negative alteri a-tions, only the former of which produce the desired damping effect. Notwithstanding this the arrangement is sufiiciently efficacious. The circuit shown in Fig. 6 is well adapted for receiving by means of a heterodyne E and a telephone H.

Fig. 7 shows a circuit arrangement in which the point 0 controlling the grids of tubes T T is located ahead of the detector D. Therefore the high frequency oscillations if sufliciently strong will cause themselves their damping. In this case the amplification that exists between points 0 and the first one L C of the damping resonators must be slight, because otherwise the receiverwould become the seat of autoenergization' phenomena.

Having described my invention, what I claim is:

1. In a receiving system, a pairrof threeelectrode tubes, a common resonant circuit connected to the grid-filament circuit of one of said tubes and to the plate-filament circuit of the other, and grid biasing means connected in the plate-filament circuit of the first tube to the grid of the second. a

2. In a receiving circuit, a three-electrode tube having a tuned input circuit and an output circuit, and a second three-electrode tube having its plate and filament electrodes connected to said-input circuit and its grid connegted with the output circuit of said first tu e.

3. In a receiving system, a detector, a resonant circuit connected to the input electrodes of said detector, and means for controlling the damping factor of said resonant circuit, comprising a thermionic valve having its output circuit connected in shunt to said resonant circuit and its grid connected through a current source to the output cir-' cuit of said detector.

5. In a receiving circuit, a resonant circuit, a three-electrode tube having its input electrodes connected to said circuit, a second three-electrode tube having its plate-filament electrode also connected to said resonant circuit, the plate-filament space of said second named tube actingas a variable resistance, and means connected between the output circuit of said first tube and the grid of said second tube to automatically control the potential on said grid and thereby the-space resistance in accordance with oscillations in the resonant circuit; i

6. In a receiving arrangement, a pair of means connected to the plate-filament circuit of said second tube, and a connection between .said last mentioned means and the grid of said first tube.

'8. The combination with a resonant circuit, of a three-electrode tube having its plate-filament circuit connected in shunt to said resonant circuit, a second three-electrode tube having its grid-filament circuit connected to said resonant circuit and a connection between the grid of said first tube an}? the plate-filament circuit of said second tu e.

9.'The combination with a resonant circuit, of a three-electrode detector tube having its input circuit connected to said resonant circuit, a second three-electrode tube having its plate-filament circuit connected in shunt to said resonant circuit, a grid biasing means connected to the plate-filament circuit of said second named tube, and a connection between the grid of said second named tube and the output circuit of said detector tube through said grid biasing means.

10. The combination with a resonant circuit, of a three-electrode detector tube having its input circuit connected thereto, a source of energy having its positive pole connected to the output circuit of said tube, a second three-electrode tube having its platefilament circuit connected in shunt to said resonant circuit, means in said plate-filament circuit for impressing a desired potential on said plate, and a conductor connected between the grid or'. said second named tube and a predetermined negative potential point of said source of energy.

HENRI JEAN JOSEPH MARIE de REGNAULD 'de BELLESCIZE.

three-electrode tubes, a common resonant circuit connected in the input circuit of one of said tubes and in the output circuit of the other, and a connection between the output 

